Download Comments-C57.21

Comments on IEEE 57.21, Shunt Reactors Rated Over 500KVA
Section
3.1.1
3.1.2
3.1.2
3.3.1 &
3.6.1
4.4.2
4.6
4.6
5.1
7.1
Table 4.A
Table 4.A
7.2.3
9.1.1 &
Table 5
10.2.1
10.2.2.1 a)
10.2.5 c)
10.2.5
10.3
10.3.3
Comment
Letter “R” missing from title word Reactor
Letter “S” missing from title word Shunt
Word “(parallel)” to be added in the sentence … for
connection in shunt (parallel) to an electric…
Letter “D” missing from title word Dry
Maximum allowed temperatures for cooling air for
higher than 3300 feet need to be lowered.
Figure 1 is missing.
Most oil immersed shunt reactors are gapped core type
and therefore exhibit very close to linear characteristics
in the unsaturated portion of the curve.
KVA rating of shunt reactor cannot be confirmed due to
variation in actual impedance v/s designed
Standard should define minimum % of rated voltage for
reduced voltage testing. My proposal is 90%.
Due to high force of attraction between core packets,
Audible sound level test to be a routine test for shunt
reactor rated 15MVAr 3 phase (or 5 MVAr 1 phase) or
above
Due to high force of attraction between core packets,
Vibration test to be a routine test for shunt reactor rated
60MVAr 3 phase (or 10 MVAr 1 phase) or above.
Sentence “For three phase shunt reactors, zero
sequence……………….. measured as indicated” is to be
deleted.
Maximum system voltages to match with Table 4 and 5
of IEEE 57.12.00.
Resistance measurement purposes: Purpose c and d of
IEEE 57.12.90, Section 5 are to be added.
Provide minimum time instead of a range ( 3 to 8 h). 3
hours minimum, in my opinion, is adequate for any size
of SR.
What is drop-of-potential method? Figure 2 is missing.
Volt-Ammeter method to be added.
Sections of dielectric tests are not in sequence of how
the dielectric test done. IEEE 57.12.90 can be considered
as good reference to re-assign section numbers.
Over voltage test (Induced) with partial discharge
measurement will require test transformer to be free of
PD. Since shunt reactors are tested at with a source that
can provide rated voltage of the shunt reactor itself, the
test transformer itself has to be one voltage level higher
Remark
10.4.3.1
10.4.3.1
10.4.3.3
10.5.7.2
10.5.8.1 &
2
than shunt reactor. For shunt reactors of345KV or
above, it may be difficult to have test transformer of
higher than 345KV class. Some consideration is to be
given for such situation.
More explanation/direction is needed as to when to use
wattmeter, bridges etc.
Figure 4, 5 and 6 are missing.
In shunt reactor, no load loss, load loss, stray loss all are
measured as load loss. Temperature co efficient of
resistance is different for different materials involved in
causing load loss. Therefore it is important to carry out
load loss test very close to the reference temperature
for accuracy sake. With that said, the actual
temperature at measurement needs to be within +/-10
deg C of reference temperature.
Since shunt reactors do not have different stages of
cooling, I wonder why this section, of self-cooled, is
needed.
Unlike transformer, shunt reactor does not have
situation of total loss run and rated current run. Hence
these two sections are not required. Correction back to
shut down is not applicable.